I've used 5.5" low profile banana cuts, 5.5" shields, 5" shields and 5" parabolics. I prefer the shield cuts for the looks. With the way the bow and arrows are tuned, I can't tell a bit of difference in the 5.5 and 5 shields with 2 blade zwickeys glued up.

Just for kicks, I hid behind a tree right next to the target butt and listened to the different arrows coming downrange. The bananas are the lowdest and man are they loud. Something on the order of B-52. The 5.5 shields are next loudest, being just this side of a buzz bomb and the 5" shields were quieter still, but still loud. The parabolics were the quietest, but with the ears that a deer has, they must sound like the end of the world coming. Hmm, actually, it probably is. Now, the softer secondary turkey wing feather is considerably more quiet than the stiffer primary. I could still hear them, but compared to the rest, they were a quiet swooosh.